Ethernet passive optical networks (EPON) are optical networks that handle Ethernet packets. The IEEE P802.3ca 100G-EPON Task Force was established in 2015. The main objective of this task force is defining the physical layer specifications and management parameters for 25 Gb/s, 50 Gb/s, and 100 Gb/s PONs. Such 50 Gb/s and 100 Gb/s optical network units (ONUs) in the 802.3ca system will contain multiple transceivers. Their traffic is transmitted via multiple wavelength channels in parallel, with each channel working at 25 Gb/s. This type of wavelength channel bonding is a key feature of the 802.3ca system.
The original media-independent interface (MII) transmitted data at 100 Mbit/s. Extensions to MII, including but not limited to reduced MII (RMII), gigabit MII (GMII), and reduced gigabit MII (RGMII), are collectively referred to as xMII.